1. Field of the Invention
This invention relates to excavation shielding and shoring systems generally comprising vertical support elements and multiple vertically positioned wall shoring panels for shoring up the walls of an excavation and to a method for shoring excavations. More particularly, this invention relates to excavation shielding and shoring systems for excavations having structures crossing through the excavation, such as utility pipelines and the like, which are installable from outside of the excavation and which are able to accommodate the crossing structures.
2. Description of Related Art
Occupational Safety and Health Administration (OSHA) regulations require that any excavation over five feet deep be properly shielded or shored to prevent cave-ins or to protect workers inside an excavation in the event of a cave-in. Trench shielding is used to protect workers from cave-ins or landslides while allowing for normal shifts and fissures of the trench face. By comparison, trench shoring is used to prevent any movement of the trench face so as not to damage nearby structures, such as building foundations and roadways.
Trench boxes, hydraulic shoring, and timber shoring are standard methods used to comply with the OSHA regulations in utility excavations. However, although these systems can provide the required support, they do not always provide the flexibility required to fit around crossing utilities and other obstacles inside the excavation. Trench boxes are large steel or aluminum boxes that are typically assembled above ground by workers at the job site and dropped inside utility trenches. However, if utility lines running perpendicular to the trench are also present, the trench boxes cannot be dropped around these crossing lines. Similarly, hydraulic shoring also is not designed to fit around crossing utility lines, especially when used in conjunction with prefabricated facing panels. By way of comparison, timber shoring is flexible enough to fit around obstructions; however, its construction is performed while the workers are inside the excavation, thereby potentially exposing the workers to unsafe conditions.
There are in existence a wide variety of excavation protective structures and shoring systems. By way of example, reissued U.S. Pat. No. Re. 30,185 to Griswold teaches a trench shoring system assembly which includes a pair of spaced apart side walls for vertical disposition within a trench interconnected by spreader pipes and collars which allow limited pivotal movement between the side walls. Similarly, U.S. Pat. No. 5,310,290 to Spencer teaches a protective structure for excavations comprising a protective panel which may be used alone or paired to provide a protective space in an excavation by buttressing the upright walls of the excavation. U.S. Pat. No. 5,302,054 teaches an excavation shoring system utilizing a plurality of shoring panels positioned between adjacent vertical soldier beams around the periphery of an excavation hole. However, none of these known systems is able to accommodate utility lines or other crossing structures passing through or running perpendicular to the trench.